LibWeb: Stub AudioContext constructor

This is enough to make Discord not throw up "Well this is awkward" on
login.

Userland/Libraries/LibWeb/WebAudio/AudioContext.h

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2023, Luke Wilde <lukew@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/WebAudio/BaseAudioContext.h>
+
+namespace Web::WebAudio {
+
+// https://webaudio.github.io/web-audio-api/#AudioContext
+class AudioContext final : public BaseAudioContext {
+    WEB_PLATFORM_OBJECT(AudioContext, BaseAudioContext);
+
+public:
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<AudioContext>> construct_impl(JS::Realm&);
+
+    virtual ~AudioContext() override;
+
+private:
+    explicit AudioContext(JS::Realm&);
+
+    virtual JS::ThrowCompletionOr<void> initialize(JS::Realm&) override;
+};
+
+}